The word "yoyo" has several antonyms depending on the context in which it is used. As a noun, antonyms for a yoyo would be things such as straight line, static, stable, and unchanging. In the sense of a person's emotions, antonyms could be steady, consistent, predictable, and level-headed. If we use yoyo as a verb, then its antonyms would be words such as steady or constant. Yoyo can also refer to the toy, in which case an antonym would be something non-rotating or non-moving. Other possible antonyms for yoyo could be anchor, stabilizer, balance, or base, depending on the context in which it is used.